In power-assisted steering systems or power steering systems having an electric motor, which drives a worm gear mechanism that includes a composite gear wheel, e.g., having a plastic ring gear, the composite gear wheel may ensure a high degree of running smoothness with high economic efficiency, when the worm gear mechanism has large dimensions and is paired with metallic wheels having a high degree of edge smoothness. Composite gear wheels are conventional.
PCT International Published Patent Application No. WO 01/44694 describes a composite gear wheel, which is suitable for a worm gear mechanism of a power-assisted steering system or power steering system, having a two-piece ring gear that is screwed onto a hub. The hub has an annular flange on one axial end. The ring gear is form-locked to the hub by a disk, which is positioned in the axial direction of the composite gear wheel, on the opposite side of the annular flange. Both the disk and the annular flange of the hub have an annular projection, which, in each instance, engages with an annular groove on the side faces of the ring gear in the axial direction of the composite gear wheel and secures the ring gear in the radial direction.
To transmit the torque from the ring gear to the hub or vice versa, threaded bolts are guided through the disk, the ring gear, and the annular flange of the hub. The individual component parts and, in particular, the threaded bolts are not self-centering, which is why the power transmission in the composite gear wheel and the assembly sequence of the composite gear wheel are not optimized.